From Neogaf, Vita release schedule:
04/19 Lumines: Electronic Symphony
04/26 Ciel Nosurge: Ushinawareta Hoshi e Sasagu Uta
NextRev: Eibunpou Tettei Tokkun
05/24 NextRev: Gyouseishoshi Shiken
Samurai & Dragons (Deluxe Package)
06/07 Hello Kitty to Issho: Block Crash V
Kidou Senshi Gundam Seed Battle Destiny
06/14 Persona 4: The Golden
Super Monkey Ball: Tokumori AsoVita!
06/28 Metal Gear Solid HD Edition
NextRev: IT Passport Shiken
NextRev: Kihonjouhou Gijutsusha Shiken
NextRev: Ouyou Jouhougijutsusha Shiken
Nothing to hold your breath for - but I think that Soul Sacrifice game will be released soon, so it might enter this list, giving it more impact. Because none of this can push Vita past 20k, I think.
I saw a different list on another site, but pretty much the same thing.
Is that Metal Gear just a port of an old Metal Gear game? Also are Vita owners in Japan waiting for Persona?